Two Knights Attack

The idea

White develops with 2.Nc3 and 3.Nf3 (2.Nf3 d5 3.Nc3 reaches the same position) and keeps the d-pawn's options open. Black's most respected answer is 3...Bg4, pinning the knight. After 4.h3 Bxf3 5.Qxf3, Black has given up the bishop for the knight and plays 5...e6, with a rock-solid pawn on d5 backed by c6 and e6. 5...Nf6 is the other main move.

Wikipedia calls this the Two Knights Variation; Lichess calls the 3...Bg4 4.h3 Bxf3 line the Mindeno Variation, Exchange Line.

Plans for White

White has the two bishops and a lead in development, and wants to open the position for them. The queen on f3 eyes the kingside and the pawn on d5, but it came out early and is exposed to Black's minor pieces, so White will often have to find it a quieter square as Black develops.

Plans for Black

Complete development with ...Nf6 and ...Nbd7, a bishop to e7 or b4, and castling. The pawns on c6, d5 and e6 are very solid, and with the light-squared bishops off the board, Black has no bad bishop to worry about. Black is happy to trade pieces and reach an endgame.

Watch out for

For Black, the Classical-style move order. 3...dxe4 4.Nxe4 Bf5 5.Ng3 Bg6 looks natural, but 6.h4 h6 7.Ne5 Bh7 8.Qh5! hits f7 with the queen and the knight, and the natural 8...Nf6?? allows 9.Qxf7, mate. That's one reason 3...Bg4 is the main line.

For Black after 4.h3, the retreat 4...Bh5 is playable but needs care: in Noteboom–Mindeno, 1927, Black lost quickly after 5.exd5 cxd5 6.g4 Bg6 7.Ne5 a6?, where 7...Nc6 was necessary. For White, the danger is drifting: if Black finishes development, the bishop pair counts for little in a closed position.